Dextran Sulfate Sodium (DSS)-Induced Acute Colitis in the Rat

High-resolution spatially resolved proteomics of complex tissues based on microfluidics and transfer learning

Despite recent advances in imaging- and antibody-based methods, achieving in-depth, high-resolution protein mapping across entire tissues remains a significant challenge in spatial proteomics. Here, we present parallel-flow projection and transfer learning across omics data (PLATO), an integrated framework combining microfluidics with deep learning to enable high-resolution mapping of thousands of proteins in whole tissue sections. We validated the PLATO framework by profiling the spatial proteome of the mouse cerebellum, identifying 2,564 protein groups in a single run. We then applied PLATO to rat villus and human breast cancer samples, achieving a spatial resolution of 25 μm and uncovering proteomic dynamics associated with disease states. This approach revealed spatially distinct tumor subtypes, identified key dysregulated proteins, and provided novel insights into the complexity of the tumor microenvironment. We believe that PLATO represents a transformative platform for exploring spatial proteomic regulation and its interplay with genetic and environmental factors.

Bacteroides vesicles promote functional alterations in the gut microbiota composition

Inflammatory bowel diseases are characterized by chronic intestinal inflammation and alterations in the gut microbiota composition. Bacteroides fragilis, which secretes outer membrane vesicles (OMVs) with polysaccharide A (PSA), can moderate the inflammatory response and possibly alter the microbiota composition. In this study, we created a murine model of chronic sodium dextran sulfate (DSS)-induced intestinal colitis and treated it with B. fragilis OMVs. We monitored the efficiency of OMV therapy by determining the disease activity index (DAI) and performing histological examination (HE) of the intestine before and after vesicle exposure. We also analyzed the microbiota composition using 16S rRNA gene sequencing. Finally, we evaluated the volatile compound composition in the animals' stools by HS-GC/MS to assess the functional activity of the microbiota. We observed more effective intestinal repair after OMV treatment according to the DAI and HE. A metabolomic study also revealed changes in the functional activity of the microbiota, with a predominance of phenol and pentanoic acid in the control group compared to the group treated with DSS and the group treated with OMVs (DSS OMVs). We also observed a positive correlation of these metabolites with Saccharibacteria and Acetivibrio in the control group, whereas in the DSS group, there was a negative correlation of phenol and pentanoic acid with Lactococcus and Romboutsia. According to the metabolome and sequencing data, the microbiota composition of the DSS-treated OMV group was intermediate between that of the control and DSS groups. OMVs not only have an anti-inflammatory effect but also contribute to the recovery of the microbiota composition.IMPORTANCEBacteroides fragilis vesicles contain superficially localized polysaccharide A (PSA), which has unique immune-modulating properties. Isolated PSA can prevent chemically induced colitis in a murine model. Outer membrane vesicles (OMVs) also contain digestive enzymes and volatile metabolites that can complement the anti-inflammatory properties of PSA. OMVs showed high therapeutic activity against sodium dextran sulfate-induced colitis, as confirmed by histological assays. 16S rRNA sequencing of fecal samples from different inflammatory stages, supplemented with comprehensive metabolome analysis of volatile compounds conducted by HS-GC/MS, revealed structural and functional alterations in the microbiota composition under the influence of OMVs. Correlation analysis of the OMV-treated and untreated experimental animal groups revealed associations of phenol and pentanoic acid with Lactococcus, Romboutsia, Saccharibacteria, and Acetivibrio.

Natural medicines-derived carbon dots as novel oral antioxidant administration strategy for ulcerative colitis therapy

BACKGROUND

Ulcerative colitis (UC) is a chronic intestinal inflammation, resulting in a global healthcare challenge with no real specific medicine. Natural medicines are recognized as a potential clinical alternative therapy, but their applications are limited by poor solubility and low bioavailability.

RESULTS

In this work, inspired by the natural medicines of ancient China, novel functional carbon dots derived from Magnetite and Medicated Leaven (MML-CDs) were synthesized by hydrothermal method, and confirmed their ultrasmall nano-size (3.2 ± 0.6 nm) and Fe doped surface structure, thereby with excellent gastrointestinal stability, remarkable capabilities in eliminating ROS, and highly biocompatibility. With no external stimuli, the oral administration of MML-CDs demonstrated obvious alleviation to UC. Further experiments pointed that MML-CDs could improve hemostasis capability, suppress inflammation reactions and oxidative stress, and up-regulate the expression of tight junction proteins. Furthermore, MML-CDs also showed well regulation in the dysbiosis of intestinal flora.

CONCLUSION

Overall, above evidence reveals that green-synthesized MML-CDs can significantly alleviate intestinal bleeding, inhibit colon inflammation, and repair colonic barrier damage, further regulating intestinal flora and intestinal inflammation microenvironment. Our findings provide an efficient oral administration of MML-CDs as a novel therapy strategy for ulcerative colitis.

Unveiling Colitis: A Journey through the Dextran Sodium Sulfate-induced Model

Animal models of inflammatory bowel disease (IBD) are valuable tools for investigating the factors involved in IBD pathogenesis and evaluating new therapeutic options. The dextran sodium sulfate (DSS)-induced model of colitis is arguably the most widely used animal model for studying the pathogenesis of and potential treatments for ulcerative colitis (UC), which is a primary form of IBD. This model offers several advantages as a research tool: it is highly reproducible, relatively easy to generate and maintain, and mimics many critical features of human IBD. Recently, it has also been used to study the role of gut microbiota in the development and progression of IBD and to investigate the effects of other factors, such as diet and genetics, on colitis severity. However, although DSS-induced colitis is the most popular and flexible model for preclinical IBD research, it is not an exact replica of human colitis, and some results obtained from this model cannot be directly applied to humans. This review aims to comprehensively discuss different factors that may be involved in the pathogenesis of DSS-induced colitis and the issues that should be considered when using this model for translational purposes.

Walnut-Derived Peptide Improves Cognitive Impairment in Colitis Mice Induced by Dextran Sodium Sulfate via the Microbiota-Gut-Brain Axis (MGBA)

In this study, we investigated the protective mechanism of walnut-derived peptide LPLLR (LP-5) against cognitive impairment induced in a dextran sodium sulfate (DSS)-induced colitis mouse model, with emphasis on the microbiota-gut-brain axis (MGBA). The results revealed that LP-5 could improve the learning ability and memory of mice with cognitive impairment and mitigate colitis symptoms, including weight loss, bloody stools, colon shortening, and histopathological changes. Additionally, LP-5 protected the integrity of the intestinal barrier by promoting the expression of tight junction proteins (TJs) while attenuating colonic inflammation by suppressing proinflammatory cytokine and epithelial cell apoptosis. Western blotting indicated that LP-5 treatment suppressed the inflammatory NF-κB/MLCK/MLC signaling pathway activity. Furthermore, LP-5 ameliorated hippocampal neuron damage and protected blood-brain barrier (BBB) integrity by downregulating microglia marker protein Iba-1, increasing TJ protein expression, and restoring the deterioration of synaptic proteins. Importantly, 16S rRNA sequencing results indicated that LP-5 reshaped the abundance of a wide range of gut microbiota at the phylum and genus levels, with increased Prevotella and Akkermansia associated with tryptophan (TRP), 5-hydroxytryptamine (5-HT), and 5-hydroxyindoleacetic acid (5-HIAA). These findings suggest that LP-5 could maintain intestinal barrier and BBB integrity, reverse gut dysbiosis, and improve learning and memory ability in colitis mice, providing novel insights into alterations of gut microbes in colitis and a potential new mechanism by which it causes cognitive impairment.

Novel Natural Carrier-Free Self-Assembled Nanoparticles for Treatment of Ulcerative Colitis by Balancing Immune Microenvironment and Intestinal Barrier

Ulcerative colitis (UC) is a chronic inflammatory illness affecting the colon and rectum, with current treatment methods being unable to meet the clinical needs of ulcerative colitis patients. Although nanomedicines are recognized as promising anti-inflammatory medicines, their clinical application is limited by their high cost and unpredictable safety risks. This study reveals that two natural phytochemicals, berberine (BBR) and hesperetin (HST), self-assemble directly to form binary carrier-free multi-functional spherical nanoparticles (BBR-HST NPs) through noncovalent bonds involving electrostatic interactions, π-π stacking, and hydrogen bonding. Because of their synergistic anti-inflammatory activity, berberine-hesperetin nanoparticles (BBR-HST NPs) exhibit significantly better therapeutic effects on UC and inhibitory effects on inflammation than BBR and HST at the same dose by regulating the immune microenvironment and repairing the damaged intestinal barrier. Furthermore, BBR-HST NPs exhibit good biocompatibility and biosafety. Thus, this study proves the potential of novel natural anti-inflammatory nanoparticles as therapeutic agents for UC, which could promote the progress of drug development for UC and eventually benefit patients who suffering from it.

Dextran Sulfate Sodium Salt (DSS) induced enteritis in Orange-spotted grouper, Epinephelus coioides

The enteritis is a common disease in fish farming, but the pathogenesis is still not fully understood. The aim of the present study was to investigate the inducement of Dextran Sulfate Sodium Salt (DSS) intestinal inflammation on Orange-spotted grouper (Epinephelus coioides). The fish were challenged with 200 μl 3% DSS via oral irrigation and feeding, an appropriate dose based on the disease activity index of inflammation. The results indicated that the inflammatory responses induced by DSS were closely associated with the expression of pro-inflammatory cytokines including interleukin 1β (IL-1β), IL-8, IL16, IL-10 and tumor necrosis factor α (TNF-α), as well as NF-κB and myeloperoxidase (MPO) activity. At day5 after DSS treatment, the highest levels of all parameters were observed. Also, the severe intestinal lesions (intestinal villus fusion and shedding), strong inflammatory cell infiltration and microvillus effacement were seen through histological examination and SEM (scanning electronic microscopy) analysis. During the subsequent 18 days of the experimental period, the injured intestinal villi were gradually recovery. These data is beneficial to further investigate the pathogenesis of enteritis in farmed fish, which is helpful for the control of enteritis in aquaculture.

New Insights of Biological Functions of Natural Polyphenols in Inflammatory Intestinal Diseases

The intestine is critically crucial for nutrient absorption and host defense against exogenous stimuli. Inflammation-related intestinal diseases, including enteritis, inflammatory bowel disease (IBD), and colorectal cancer (CRC), are heavy burdens for human beings due to their high incidence and devastating clinical symptoms. Current studies have confirmed that inflammatory responses, along with oxidative stress and dysbiosis as critical pathogenesis, are involved in most intestinal diseases. Polyphenols are secondary metabolites derived from plants, which possess convincible anti-oxidative and anti-inflammatory properties, as well as regulation of intestinal microbiome, indicating the potential applications in enterocolitis and CRC. Actually, accumulating studies based on the biological functions of polyphenols have been performed to investigate the functional roles and underlying mechanisms over the last few decades. Based on the mounting evidence of literature, the objective of this review is to outline the current research progress regarding the category, biological functions, and metabolism of polyphenols within the intestine, as well as applications for the prevention and treatment of intestinal diseases, which might provide ever-expanding new insights for the utilization of natural polyphenols.

Assessing acute colitis induced by dextran sulfate sodium in rats and its impact on gastrointestinal fluids

Dextran sulfate sodium (DSS) is commonly used to induce colitis in rats. While the DSS-induced colitis rat model can be used to test new oral drug formulations for the treatment of inflammatory bowel disease, the effect of the DSS treatment on the gastrointestinal tract has not been thoroughly characterized. Additionally, the use of different markers to assess and confirm successful induction of colitis is somewhat inconsistent. This study aimed to investigate the DSS model to improve the preclinical evaluation of new oral drug formulations. The induction of colitis was evaluated based on the disease activity index (DAI) score, colon length, histological tissue evaluation, spleen weight, plasma C-reactive protein, and plasma lipocalin-2. Furthermore, the study investigated how the DSS-induced colitis affected the luminal pH, lipase activity, and concentrations of bile salts, polar lipids, and neutral lipids. For all evaluated parameters, healthy rats were used as a reference. The DAI score, colon length, and histological evaluation of the colon were effective disease indicators in DSS-induced colitis rats, while spleen weight, plasma C-reactive protein, and plasma lipocalin-2 were not. The luminal pH of the colon and bile salt- and neutral lipid concentrations in regions of the small intestine were lower in DSS-induced rats compared to healthy rats. Overall, the colitis model was deemed relevant for investigating ulcerative colitis-specific formulations.

A novel oral formulation of the melanocortin-1 receptor agonist PL8177 resolves inflammation in preclinical studies of inflammatory bowel disease and is gut restricted in rats, dogs, and humans

Introduction

PL8177 is a potent and selective agonist of the melanocortin 1 receptor (MC1R). PL8177 has shown efficacy in reversing intestinal inflammation in a cannulated rat ulcerative colitis model. To facilitate oral delivery, a novel, polymer-encapsulated formulation of PL8177 was developed. This formulation was tested in 2 rat ulcerative colitis models and evaluated for distribution, in vivo, in rats, dogs, and humans.

Methods

The rat models of colitis were induced by treatment with 2,4-dinitrobenzenesulfonic acid or dextran sulfate sodium. Single nuclei RNA sequencing of colon tissues was performed to characterize the mechanism of action. The distribution and concentration of PL8177 and the main metabolite within the GI tract after a single oral dose of PL8177 was investigated in rats and dogs. A phase 0 clinical study using a single microdose (70 µg) of [14C]-labeled PL8177 investigated the release of PL8177 in the colon of healthy men after oral administration.

Results

Rats treated with 50 µg oral PL8177 demonstrated significantly lower macroscopic colon damage scores and improvement in colon weight, stool consistency, and fecal occult blood vs the vehicle without active drug. Histopathology analysis resulted in the maintenance of intact colon structure and barrier, reduced immune cell infiltration, and increased enterocytes with PL8177 treatment. Transcriptome data show that oral PL8177 50 µg treatment causes relative cell populations and key gene expressions levels to move closer to healthy controls. Compared with vehicle, treated colon samples show negative enrichment of immune marker genes and diverse immune-related pathways. In rats and dogs, orally administered PL8177 was detected at higher amounts in the colon vs upper GI tract. [14C]-PL8177 and the main metabolite were detected in the feces but not in the plasma and urine in humans. This suggests that the parent drug [14C]-PL8177 was released from the polymer formulation and metabolized within the GI tract, where it would be expected to exert its effect.

Conclusion

Collectively, these findings support further research into the oral formulation of PL8177 as a possible therapeutic for GI inflammatory diseases in humans.

The Effect of Necrosis Inhibitor on Dextran Sulfate Sodium Induced Chronic Colitis Model in Mice

Uncontrolled chronic inflammation and necrosis is characteristic of inflammatory bowel disease (IBD). This study aimed to investigate the effect of necrosis inhibitor (NI, NecroX-7) on a dextran sulfate sodium (DSS) induced chronic colitis model of mice. DSS was administered on days 1-5, and the NI was administered intraperitoneally (3 mg/kg, 30 mg/kg) on days 1, 3, and 5 as well as every other day during the first five days of a three-week cycle. Three cycles of administration were performed. Colitis was evaluated based on the disease activity index (DAI) score, colon length, and histological score. Reverse transcription polymerase chain reaction testing, the Western blot assay, and immunohistochemical staining were performed to determine inflammatory cytokine levels. The NI reduced body weight change and the DAI score. Colon length and the histological score were longer and lower in the NI-treated groups, respectively. The NI decreased the expression of pro-inflammatory cytokines, particularly in tumor necrosis factor alpha (TNF-α) and phosphorylated nuclear factor kappa B (p-NF-κB). Immunohistochemical staining revealed decreased inducible nitric oxide synthase (iNOS) and high mobility group box 1 (HMGB1) levels. Overall, the NI improved DSS induced chronic colitis by attenuating the mRNA expression of pro-inflammatory cytokines such as TNF-α. Therefore, NI use is a potential, novel treatment approach for IBD.

Colitis induced by dextran sulphate sodium causes histopathological and immunological changes in the periodontal tissues of Wistar rats

OBJECTIVE

This study investigated the impact of colitis induced by dextran sulphate sodium (DSS)-induced colitis (DIC) on histopathological and immunological outcomes in the periodontal tissues of Wistar rats.

BACKGROUND

Inflammatory bowel diseases (IBD) and periodontitis have been reported to present a bidirectional relationship. However, the inflammatory pathway that connects both diseases needs further investigation.

MATERIAL AND METHODS

Twenty-five male Wistar rats were allocated in four groups: unilateral ligature-induced periodontitis for 14 days: LIP (n = 7); dextran sulphate sodium-induced colitis only: DIC (n = 6); DIC + LIP (n = 6) and controls (n = 6). Digital images were obtained from the histological sections. In order to assess the attachment loss (AL), the linear distance between the cementoenamel junction (CEJ) and the alveolar bone crest was measured on the mesial root using histological photomicrography's ImageJ software. Immunological analyses of gingival tissues and plasma were performed by Bio-Plex Th1/Th2 Assay.

RESULTS

The DIC group showed inflammatory cells extending to the periodontal connective tissues, which contained significantly elevated expressions of IL-1α, IL-1β, IL-2, IL-6, IL-12, IL-13, GM-CSF, IFN-γ and TNF-α compared to controls. There was no significant difference in bone loss between controls and DIC. There were no significant histopathological differences between DIC + LIP and LIP. However, DIC + LIP presented a significantly lower IL-2 and IL-5 than the LIP group. There was no bone loss difference between LIP+DIC and LIP groups. DIC + LIP group presented significantly higher levels of GM-CSF in plasma.

CONCLUSION

DSS-induced colitis was associated with an overexpression of Th1/Th2- related cytokines in the gingival tissue.

Collagen peptide promotes DSS-induced colitis by disturbing gut microbiota and regulation of macrophage polarization

Ulcerative colitis (UC) is an inflammatory bowel disease caused by mucosal immune system disorder, which has increased steadily all over the world. Previous studies have shown that collagen peptide (CP) has various beneficial biological activities, it is not clear whether the effect of CP on UC is positive or negative. In this study, 2.5% dextran sulfate sodium (DSS) was used to establish acute colitis in mice. Our results suggested that CP supplementation (200, 400 mg/kg/day) promoted the progression of colitis, increased the expression of inflammatory factors and the infiltration of colonic lamina propria macrophages. Gut microbiota analysis showed the composition changed significantly and inflammation promoted bacteria was after CP treatment. Meanwhile, the effect of CP on macrophage polarization was further determined in Raw264.7 cell line. The results showed that CP treatment could increase the polarization of M1 macrophages and promote the expression of inflammatory factors. In conclusion, our results showed that CP treatment could disrupt the gut microbiota of host, promote macrophage activation and aggravate DSS-induced colitis. This may suggest that patients with intestinal inflammation should not take marine derived CP.

Does a single exposure to social defeat render rats more vulnerable to chemically induced colitis than brief inescapable foot-shocks?

All mammals are to different degrees exposed to stressors being physical or social, which may affect health and well-being. Stressful and traumatic situations have direct effects on immune responses that may alter susceptibility to developing somatic illnesses. In animal research, different types of stressors have been investigated in studying the effect on bowel disorders, some stressors being more or less of environmental origin. We aimed, therefore, to explore whether a more natural stressor would differ from a stressor of more unnatural characteristics on dextran sulphate sodium (DSS) induced colitis in adult rats. Specifically, whether social stress within a single social defeat (SD) paradigm would be a more potent stressor than brief inescapable foot-shocks (IFS) in causing elevated faecal granulocyte marker protein (GMP), and crypt- and inflammation scores in colonic tissue. Three groups of male Wistar rats were used; socially defeated rats; inescapable foot-shock rats; and comparison rats. Main findings showed no difference between the groups on GMP levels. However, there was a significant difference on inflammation and crypt scores for the distal part of colon, detected through histology, where socially defeated rats were more susceptible. A single SD seems to be more adverse than inescapable foot-shock on DSS induced colitis, but further studies are recommended to validate a broader range of different outcomes comparing two such different rodent stress models.

Dextran Sulphate Sodium Acute Colitis Rat Model: A Suitable Tool for Advancing Our Understanding of Immune and Microbial Mechanisms in the Pathogenesis of Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a group of disorders causing inflammation in the digestive tract. Recent data suggest that dysbiosis may play a pivotal role in the IBD pathogenesis. As microbiome-based therapeutics that modulate the gut ecology have been proposed as a novel strategy for preventing IBD, the aim of presenting study was to evaluate the dextran sulphate sodium (DSS) rat model mainly in terms of microbial shifts to confirm its suitability for dysbiosis study in IBD. Acute colitis was induced using 5% DSS solution for seven days and rats were euthanized five days after DSS removal. The faecal/caecal microbiota was analyzed by next generation sequencing. Disease activity index (DAI) score was evaluated daily. Blood and colon tissue immunophenotyping was assessed by flow cytometry and histological, haematological, and biochemical parameters were also evaluated. The colitis induction was reflected in a significantly higher DAI score and changes in all parameters measured. This study demonstrated significant shifts in the colitis-related microbial species after colitis induction. The characteristic inflammation-associated microbiota could be detected even after a five day-recovery period. Moreover, the DSS-model might contribute to an understanding of the effect of different treatments on extraintestinal organ impairments. The observation that certain bacterial species in the gut microbiota are associated with colitis raises the question of whether these organisms are contributors to, or a consequence of the disease. Despite some limitations, we confirmed the suitability of DSS-induced colitis model to monitor microbial changes during acute colitis, in order to test attractive new microbiome-based therapies.

Mechanisms modulating the activities of intestinal stem cells upon radiation or chemical agent exposure

Intestinal stem cells (ISCs) are essential for the regeneration of intestinal cells upon radiation or chemical agent damage. As for radiation-induced damage, the expression of AIM2, YAP, TLR3, PUMA or BVES can aggravate ISCs depletion, while the stimulation of TLR5, HGF/MET signaling, Ass1 gene, Slit/Robo signaling facilitate the radio-resistance of ISCs. Upon chemical agent treatment, the activation of TRAIL or p53/PUMA pathway exacerbate injury on ISCs, while the increased levels of IL-22, β-arrestin1 can ease the damage. The transformation between reserve ISCs (rISCs) maintaining quiescent states and active ISCs (aISCs) that are highly proliferative has obtained much attention in recent years, in which ISCs expressing high levels of Hopx, Bmi1, mTert, Krt19 or Lrig1 are resistant to radiation injury, and SOX9, MSI2, clusterin, URI are essential for rISCs maintenance. The differentiated cells like Paneth cells and enteroendocrine cells can also obtain stemness driven by radiation injury mediated by Wnt or Notch signaling. Besides, Mex3a-expressed ISCs can survive and then proliferate into intestinal epithelial cells upon chemical agent damage. In addition, the modulation of symbiotic microbes harboring gastrointestinal (GI) tract is also a promising strategy to protect ISCs against radiation damage. Overall, the strategies targeting mechanisms modulating ISCs activities are conducive to alleviating GI injury of patients receiving chemoradiotherapy or victims of nuclear or chemical accident.

Immunomodulatory peptides-A promising source for novel functional food production and drug discovery

Immunomodulatory peptides are a complex class of bioactive peptides that encompasses substances with different mechanisms of action. Immunomodulatory peptides could also be used in vaccines as adjuvants which would be extremely desirable, especially in response to pandemics. Thus, immunomodulatory peptides in food of plant origin could be regarded both as valuable suplements of novel functional food preparation and/or as precursors or possible active ingredients for drugs design for treatment variety of conditions arising from impaired function of immune system. Given variety of mechanisms, different tests are required to assess effects of immunomodulatory peptides. Some of those effects show good correlation with in vivo results but others, less so. Certain plant peptides, such as defensins, show both immunomodulatory and antimicrobial effect, which makes them interesting candidates for preparation of functional food and feed, as well as templates for design of synthetic peptides.

Nanoparticle-assembled bioadhesive coacervate coating with prolonged gastrointestinal retention for inflammatory bowel disease therapy

A key challenge for the effective treatment of gastrointestinal diseases including inflammatory bowel disease is to develop an orally administered drug delivery system capable of prolonged retention in the gastrointestinal tract. Herein we report a bioadhesive liquid coacervate based on hydrogen bonding-driven nanoparticle assembly. Free from electrostatic interactions, our fluid nanoparticle-assembled coacervate demonstrates significant pH- and salt-independent structural stability and forms a physically adhesive coating on a large surface area of intestinal tract with an extended residence time of more than 2 days to mediate the sustained release of preloaded water-soluble small molecule drugs in vivo. The orally administered drug-laden nanoparticle-assembled coacervate significantly mitigates the symptoms of inflammatory bowel disease, restores the diversity of gut microbiota, reduces systemic drug exposure, and improves the therapeutic efficacy in a rat acute colitis model compared with the oral administration of the same amount of drug in solution form. We suggest that the nanoparticle-assembled coacervate provides a promising drug delivery platform for management and treatment of numerous gastrointestinal diseases where controlled drug release with extended residence time is desired.

Dynamic Properties of the Intestinal Ecosystem Call for Combination Therapies, Targeting Inflammation and Microbiota, in Ulcerative Colitis

BACKGROUND & AIMS

Intestinal microbiota-host interactions play a major role in health and disease. This has been documented at the microbiota level ("dysbiosis" in chronic immune-mediated diseases) and through the study of specific bacteria-host interactions but rarely at the level of intestinal ecosystem dynamics. However, understanding the behavior of this ecosystem may be key to the successful treatment of disease. We recently postulated that health and disease represent alternative stable states of the intestinal ecosystem (different configurations that can exist under identical external conditions), which would require adapted strategies in disease treatment. Here, we examine if alternative stable states indeed exist in this ecosystem and if they could affect remission from ulcerative colitis (UC).

METHODS

We analyzed data from a study on pediatric UC. The data reflect current treatment practice following the recruitment of treatment-naive patients with new-onset disease. Patients received personalized anti-inflammatory treatments over a period of 1 year. Stool samples at 0, 4, 12, and 52 weeks allowed an estimation of microbiota status (through 16S ribosomal RNA gene sequencing) and host inflammatory status (through the measurement of fecal calprotectin levels).

RESULTS

We identify 4 microbiota states and 4 host states. Longitudinal data show that the improvement of inflammatory status is accompanied by an improvement of microbiota status. However, they also provide strong indications that both improvements are retarded or blocked by alternative states barriers.

CONCLUSIONS

Our observations strongly suggest that inflammation suppression should be combined with microbiota management where possible to improve the efficacy of UC treatment.

Gut-liver-axis: Barrier function of liver sinusoidal endothelial cell

Liver diseases are associated with the leaky gut via the gut-liver-axis. Previous studies have paid much attention to the effect of gut barrier damage. Notably, clinical observations and basic research reveal that the gut barrier damage seldom leads to liver injury independently but aggravates pre-existing liver diseases such as non-alcoholic fatty liver disease and drug-induced liver injury. These evidences suggest that there is a hepatic barrier in the gut-liver-axis, protecting the liver against gut-derived pathogenic factors. However, it has never been investigated which type of liver cell plays the role of hepatic barrier. Under physiological conditions, liver sinusoidal endothelial cell (LSEC) can take up and eliminate virus, bacteriophage, microbial products, and metabolic wastes. LSEC also keeps the homeostasis of liver immune environment via tolerance-inducing and anti-inflammatory functions. In contrast, under pathological conditions, the clearance function of LSEC is impaired, and LSEC turns into a pro-inflammatory pattern. Given its anatomical position and physiological functions, LSEC is proposed as the hepatic barrier in the gut-liver-axis. In this review, we aim to further understand the role of LSEC as the hepatic barrier. Future studies are warranted to seek effective treatments to improve LSEC health, which appears to be a promising approach to prevent gut-derived liver injury.

Quyu Shengxin Decoction Alleviates DSS-Induced Ulcerative Colitis in Mice by Suppressing RIP1/RIP3/NLRP3 Signalling

Purpose

To study the therapeutic effect of Quyu (QY) Shengxin (SX) decoction (QYSXD) in mice with dextran sulfate sodium- (DSS-) induced ulcerative colitis and to investigate the effects of QYSXD on the regulation of the receptor-interacting protein kinase 1 (RIP1)/receptor-interacting protein kinase 3 (RIP3)/nucleotide-binding oligomerization domain-like receptor family pyrin domain protein 3 (NLRP3) signaling pathway.

Method

Thirty-six mice were randomly divided into the following 6 groups: the experimental group (QYSX group), the model group (DSS group), the positive control group (5-aminosalicylic acid (5-ASA) group), the control group, the first component group (QY group), and the second component group (SX group). Each group included 6 mice. Ulcerative colitis (UC) was induced in the mice by providing 3.5% DSS in drinking water. The mice were weighed every day to evaluate the disease activity index (DAI). After 7 days, the mice were sacrificed, and colonic tissues were obtained for colon length measurement. The morphological changes in the colon and the pathological scores of the mice in each group were observed by hematoxylin-eosin (HE) staining. The messenger ribonucleic acid (mRNA) and protein expression levels of RIP1, RIP3, dynamin-related protein 1 (Drp1), NLRP3, cysteinyl aspartate specific proteinase-1 (caspase-1), interleukin (IL)-1β, and IL-18 in the colon tissues of the mice in each group were detected and compared by real-time quantitative reverse transcription PCR (RT-qPCR) and enzyme-linked immunosorbent assay (ELISA). The levels of RIP1, RIP3, NLRP3, IL-1β, and IL-8 in the colonic mucosa were detected by ELISA. Western blotting was used to compare the protein expression of Drp1, caspase-1, mitochondrial fission protein 1 (FIS1), and mitophagy-associated protein light chain 3a/b (LC3a/b) among groups. The levels of reactive oxygen species (ROS) in the colonic mucosal cells were compared by immunofluorescence.

Results

Compared with those in the DSS group, the mice with DSS-induced colitis in the QYSX group exhibited clearly higher body weights (P < 0.05) and DAI scores (P < 0.05). The colon lengths of the mice in the QYSX group were longer than those in the DSS group (P < 0.05), and the pathological score of the QYSX group was lower than that of the DSS group (P < 0.05). The RIP1, RIP3, Drp1, IL-1β, IL-18, and caspase-1 mRNA levels in the QYSX, 5-ASA, SX, and QY groups were significantly lower than those in the DSS group (P < 0.05), but there were no differences between the QYSX group and the 5-ASA group. The levels of RIP1, RIP3, NLRP3, IL-1β, and IL-18 in the QYSX group were lower than those in the DSS group (P < 0.01). The levels of Drp1, caspase-1, FIS1, and LC3a/b in the QYSX group and the 5-ASA group were lower than those in the DSS group (P < 0.05). The levels of ROS in the colonic mucosal cells in the QYSX, 5-ASA, and QY groups were lower than those in the DSS group (P < 0.05).

Conclusion

QYSXD has certain therapeutic effects on DSS-induced colitis in mice and may be as effective as 5-ASA. QY and SX decoctions also have certain effects on colitis; however, these decoctions are not as beneficial as QYSXD. QYSXD may ameliorate colitis by inhibiting the expression of RIP1/RIP3/NLRP3 pathway-related proteins and reversing mitochondrial dysfunction to control inflammation.

Chronic colitis exacerbates NLRP3-dependent neuroinflammation and cognitive impairment in middle-aged brain

BACKGROUND

Neuroinflammation is a major driver of age-related brain degeneration and concomitant functional impairment. In patients with Alzheimer's disease, the most common form of age-related dementia, factors that enhance neuroinflammation may exacerbate disease progression, in part by impairing the glymphatic system responsible for clearance of pathogenic beta-amyloid. Inflammatory bowel diseases (IBDs) induce neuroinflammation and exacerbate cognitive impairment in the elderly. The NACHT-LRR and pyrin (PYD) domain-containing protein 3 (NLRP3) inflammasome has been implicated in neuroinflammation. Therefore, we examined if the NLRP3 inflammasome contributes to glymphatic dysfunction and cognitive impairment in an aging mouse model of IBD.

METHODS

Sixteen-month-old C57BL/6J and NLRP3 knockout (KO) mice received 1% wt/vol dextran sodium sulfate (DSS) in drinking water to model IBD. Colitis induction was confirmed by histopathology. Exploratory behavior was examined in the open field, associative memory by the novel-object recognition and Morris water maze tests, glymphatic clearance by in vivo two-photon imaging, and neuroinflammation by immunofluorescence and western blotting detection of inflammatory markers.

RESULTS

Administration of DSS induced colitis, impaired spatial and recognition memory, activated microglia, and increased A1-like astrocyte numbers. In addition, DSS treatment impaired glymphatic clearance, aggravated amyloid plaque accumulation, and induced neuronal loss in the cortex and hippocampus. These neurodegenerative responses were associated with increased NLRP3 inflammasome expression and accumulation of gut-derived T lymphocytes along meningeal lymphatic vessels. Conversely, NLRP3 depletion protected against cognitive dysfunction, neuroinflammation, and neurological damage induced by DSS.

CONCLUSIONS

Colitis can exacerbate age-related neuropathology, while suppression of NLRP3 inflammasome activity may protect against these deleterious effects of colitis.

Dextran Sodium Sulphate-Induced Gastrointestinal Injury Further Aggravates the Impact of Galantamine on the Gastric Myoelectric Activity in Experimental Pigs

Galantamine has been used as a treatment for Alzheimer disease. It has a unique, dual mode of action (inhibitor of acetylcholinesterase and allosteric modulator of nicotinic acetylcholine receptors). Nausea (in about 20%), vomiting (10%) and diarrhoea (5–7%) are the most common side effects. The aim of this study was to assess the effect of galantamine on porcine gastric myoelectric activity without (Group A) and with (Group B) dextran sodium sulphate (DSS)-induced gastrointestinal injury. Galantamine hydrobromide was administrated to twelve pigs as a single intragastric dose (24 mg). Gastric myoelectric activity was investigated by electrogastrography (EGG). Basal (15 min before galantamine administration) and study recordings after galantamine administration (300 min) were evaluated using a running spectral analysis. Results were expressed as dominant frequency of gastric slow waves and power analysis (areas of amplitudes). Altogether, 3780 one-minute EGG recordings were evaluated. In Group A, power was steady from basal values for 180 min, then gradually decreased till 270 min (p = 0.007). In Group B, there was a rapid gradual fall from basal values to those after 120 min (p = 0.007) till 300 min (p ˂ 0.001). In conclusion, galantamine alone revealed an unfavourable effect on porcine myoelectric activity assessed by gastric power. It can be a plausible explanation of galantamine-associated dyspepsia in humans. DSS caused further profound decrease of EGG power. That may indicate that underlying inflammatory, ischaemic or NSAIDs-induced condition of the intestine in humans can have aggravated the effect of galantamine on gastric myoelectric activity.

A20 functions as a negative regulator in macrophage for DSS-induced colitis

The function of A20 as a deubiquitinating enzyme in inflammatory diseases and autoimmune diseases has been reported, we therefore aimed to investigate the potential effects of A20 in macrophages and dextran sodium sulfate (DSS)-induced colitis mouse model. Colitis mouse model was induced by DSS treatment. Tnfaip3^fl/fl mice were crossed with Lyz2-Cre mice to generate A20 myeloid cell-conditional knockout mice. The expression levels of indicated cytokines were analyzed by quantitative reverse transcriptase real-time polymerase chain reaction and enzyme-linked immunosorbent assay. Phosphorylated and total protein levels in nuclear factor kappa B (NF-κB) signaling pathway were detected by Western blot. In the bone marrow of mice, A20 deficiency did not affect macrophage development. In bone marrow-derived macrophages (BMDMs) after lipopolysaccharide (LPS) treatment, A20 deficiency enhanced pro-inflammatory cytokine expression. A20 deficiency in macrophages led to severe symptoms of DSS-induced colitis in mice. A20 deficiency enhanced the NF-κB signaling pathway activity in BMDMs. The effects of A20 deficiency in DSS-induced colitis were suppressed by NF-κB pathway inhibition. A20/inhibitor of NF-κB kinase 2 (IKKβ)-double knockout mice were resistant to DSS-induced colitis. A20 suppresses pro-inflammatory cytokine expression in macrophages through the NF-κB signal pathway and alleviates the pathogenesis of DSS-induced colitis in mice.

Combined effect of vitamin C and vitamin D3 on intestinal epithelial barrier by regulating Notch signaling pathway

Background

Tight junction proteins play crucial roles in maintaining the intestinal mucosal barrier. Although previous studies have shown that Notch signaling is closely related to tight junction proteins, the mechanism remains unclear. This study was performed to investigate whether vitamin C combined with vitamin D₃ affects intestinal mucosal barrier stability via the Notch signaling pathway.

Methods

Intestinal epithelial barrier and notch signaling pathway were studied using guinea pig and SW480 cells. The guinea pigs were randomized into four groups (n = 6 in each group): control group (C, 200 IU/kg d VD₃ + 100 mg/kg d VC), low VC group (LVC, 200 IU/kg d VD₃ + 10 mg/kg d VC), medium VC group (MVC, 200 IU/kg d VD₃ + 100 mg/kg d VC), and high VC group (HVC, 200 IU/kg d VD₃ + 200 mg/kg d VC). Except for the control group, the other three groups were freely drinked with 2% dextran sodium sulfate solution for 4 days. And the control group was free to drink distilled water. The following cell groups were used: control group (SW480 cells without intervention); LPS group (100 ng/mL LPS); VD₃ group (0.1 μmol/L VD₃); VC + VD₃ group (0.1, 1, 5, 10 μmol/mL VC + 0.1 μmol/L VD₃).

Results

Electron microscopy analysis revealed that both low and high doses of vitamin C combined with vitamin D₃ maintained dextran sodium sulfate-induced ulcerative colitis in the guinea pig intestinal epithelium tight junction. Compared with the control group, the expression level of ZO-1 mRNA in the colon tissue of the high-dose vitamin C group was significantly increased. In SW480 cell experiments, compared with the control group, cell migration and repair following treatment with different concentrations of vitamin C combined with vitamin D₃ were significantly improved and the protein expression of Notch-1 was increased, whereas the protein expression of claudin-2 was significantly decreased. Thus, our results demonstrate that an appropriate amount of vitamin C combined with vitamin D₃ can regulate the expression of claudin-2 by regulating Notch-1, relieve destruction of the intestinal mucosal barrier, and promote the repair of damage to the cell mucosal barrier.

Conclusions

We found that vitamin C combined with vitamin D₃ protected against dextran sodium sulfate-induced ulcerative colitis in the guinea pig intestinal mucosa.

Xi Lei San Attenuates Dextran Sulfate Sodium-Induced Colitis in Rats and TNF-α-Stimulated Colitis in CACO2 Cells: Involvement of the NLRP3 Inflammasome and Autophagy

Objective

Inflammatory bowel disease (IBD) is a chronic nonspecific inflammatory bowel disease with an unclear etiology. The active ingredients of traditional Chinese medicines (TCMs) exert anti-inflammatory, antitumor, and immunomodulatory effects, and their multitarget characteristics provide them with a unique advantage for treating IBD. However, the therapeutic effects and underlying mechanisms of Xi Lei San in treatment of IBD remain unknown. This study was designed to investigate whether Xi Lei San exerted an anti-inflammatory effect in IBD via a mechanism involving NLRP3 inflammasomes and autophagy.

Methods

We successfully established a rat model of dextran sulfate sodium- (DSS-) induced colitis as well as a cellular model of TNF-α-induced colitis. Xi Lei San and indirubin were identified by HPLC analysis. Rats were treated with Xi Lei San or alum crystals, and their body weights and morphology of intestinal tissues were examined. A western blot analysis was performed to determine the expression levels of inflammasome-related proteins and autophagy-related proteins, ELISA was performed to analyze IL-1β, IL-18, and IL-33 concentrations, and flow cytometry was used to monitor cell apoptosis and ROS levels.

Results

Xi Lei San and indirubin were identified by HPLC analysis. We found that Xi Lei San could significantly increase the weights of rats and improve the structure of the intestinal tissues in DSS-induced colitis model rats. We also found that Xi Lei San significantly inhibited NLRP3 inflammasome activity, reduced the levels of inflammatory cytokines, and suppressed autophagy in DSS-induced colitis model rats. In vitro experiments revealed that Xi Lei San could repress apoptosis as well as ROS and inflammatory cytokine production in TNF-α-induced CACO2 cells by reducing the activity of NLRP3 inflammasomes and autophagy.

Conclusions

Our findings showed that Xi Lei San significantly ameliorated IBD by inhibiting NLRP3 inflammasome, autophagy, and oxidative stress.

Transitional changes in gastrointestinal transit and rectal sensitivity from active to recovery of inflammation in a rodent model of colitis

Patients with ulcerative colitis are typically suspected of an inflammatory flare based on suggestive symptoms of inflammation. The aim of this study was to evaluate the impact of inflammation on colonic motility and rectal sensitivity from active to recovery of inflammation. Male rats were given drinking water with 5% dextran sulfate sodium for 7 days. Inflammation, intestinal motor and sensory functions were investigated weekly for 6 weeks. (1) The disease activity index score, fecal calprotectin and tumor necrosis factor alpha were increased from Day 0 to Day 7 (active inflammation) and then decreased gradually until recovery. (2) Distal colon transit was accelerated on Day 7, and then remained unchanged. Whole gut transit was delayed on Day 7 but accelerated from Day 14 to Day 42. (3) Rectal compliance was unaffected from Day 0 to Day 7, but decreased afterwards. (4) Rectal hypersensitivity was noted on Day 7 and persistent. (5) Plasma acetylcholine was decreased on Day 7 but increased from Day 14 to Day 42. Nerve growth factor was increased from Day 7 to Day 42. DSS-induced inflammation leads to visceral hypersensitivity that is sustained until the resolution of inflammation, probably mediated by NGF. Rectal compliance is reduced one week after the DSS-induced inflammation and the reduction is sustained until the resolution of inflammation. Gastrointestinal transit is also altered during and after active colonic inflammation.

An appraisal of the gut health modulatory effects of a calf faecal-origin probiotic Lactobacillus salivarius CPN60 using Wistar rats with dextran sulfate sodium-induced colitis

BACKGROUND

Probiotics of varied origins are being developed for augmenting the gut health of human and animals. The present study aimed to evaluate the effect of a calf-origin probiotic supplement on the gut health of Wistar rats for both healthy and colitis conditions.

RESULTS

Forty-eight rats were randomly distributed into four equal groups. The 42-day study involved feeding basal diet alone (CON) or diet supplemented with the calf-origin Lactobacillus salivarius strain CPN60 (PRO). The third (CONc) and fourth (PROc) groups of rats also received the same dietary treatments (CON and PRO, respectively) but were subjected to dextran sulfate sodium (DSS)-induced colitis after 32 days of feeding. The results of a digestion trial conducted after 5 days of DSS administration revealed no influence of probiotic on the digestibility of nutrients. However, the reduced digestibility of protein and fat seen in the CONc rats was improved in the PROc group. The concentrations of lactate and acetate, propionate and butyrate, as well as total short-chain fatty acids (SCFA), were increased (P < 0.05) in the caecal and colonic digesta upon probiotic supplementation, together with significantly reduced colonic ammonia levels. Furthermore, there were reductions (P < 0.05) in acetate, butyrate and total SCFA levels in the caecal contents as a result of colitis. Probiotic supplementation increased (P < 0.05) lactobacilli and bifidobacteria counts in the colon, whereas clostridia and coliform counts were reduced (P < 0.05). These were reversed by the probiotic supplementation.

CONCLUSION

Dietary supplementation of L. salivarius CPN60 had a positive effect with respect to improving the overall gut health of healthy rats, as well as that of rats exposed to experimental colitis. © 2020 Society of Chemical Industry.

The Role of Autophagy in Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is an idiopathic intestinal inflammatory disease, including ulcerative colitis (UC) and Crohn’s disease (CD). The abnormality of inflammatory and immune responses in the intestine contributes to the pathogenesis and progression of IBD. Autophagy is a vital catabolic process in cells. Recent studies report that autophagy is highly involved in various kinds of diseases, especially inflammation-related diseases, such as IBD. In this review, the biological characteristics of autophagy and its role in IBD will be described and discussed based on recent literature. In addition, several therapies for IBD through modulating the inflammasome and intestinal microbiota taking advantage of autophagy regulation will be introduced. We aim to bring new insight in the exploration of mechanisms for IBD and development of novel therapeutic strategies against IBD.

Electroacupuncture at ST36 Relieves Visceral Hypersensitivity via the NGF/TrkA/TRPV1 Peripheral Afferent Pathway in a Rodent Model of Post-Inflammation Rectal Hypersensitivity

Purpose

The aim of the study was to investigate the effects of electroacupuncture (EA) at ST36 on rectal hypersensitivity and compliance in DSS-treated post-inflammation rats. In addition, we explored the involvement of mast cells-triggered NGF/TrkA/TRPV1 peripheral afferent pathway.

Methods

Rats were provided water with 5% dextran sulphate sodium (DSS) for 7 days. Two weeks after the DSS treatment they were subjected to initial and repetitive EA. Different sets of parameters were compared in the initial test and then EA with the selected parameters were performed for 2 weeks. Rectal compliance was assessed by colorectal distension while visceral sensitivity was evaluated by abdominal withdraw reflexes (AWR) and electromyogram (EMG). Masson's trichrome staining was performed to stain collagen and toluidine blue staining was applied to assess the degranulation of mast cells. Nerve growth factor (NGF), tryptase, TrkA and TRPV1 were measured by Western blot or immunofluorescence staining.

Results

EA at 100 Hz was more effective in improving rectal compliance and visceral hypersensitivity. Daily EA improved visceral hypersensitivity but not rectal compliance. Five weeks after DSS treatment, fibrosis was noted in both sham-EA and EA groups. The expression and activation of mast cells were significantly reduced after the 2-week EA treatment with a concurrent decrease in the expression of colonic NGF/TrkA and TRPV1 in both colon and dorsal root ganglions.

Conclusion

EA at ST36 with a special set of parameters has no effect on reduced rectal compliance but relieves visceral hypersensitivity via the mast cells-triggered NGF/TrkA/TRPV1 peripheral afferent pathway in DSS-treated post-inflammation rats.

Cell Wall Contents of Probiotics (Lactobacillus species) Protect Against Lipopolysaccharide (LPS)-Induced Murine Colitis by Limiting Immuno-inflammation and Oxidative Stress

Currently, there are no effective therapeutic agents to limit intestinal mucosal damage associated with inflammatory bowel disease (IBD). Based on several clinical studies, probiotics have emerged as a possible novel therapeutic strategy for IBD; however, their possible mechanisms are still poorly understood. Although probiotics in murine and human improve disease severity, very little is known about the specific contribution of cell wall contents of probiotics in IBD. Herein, we investigated the protective effects of cell wall contents of three Lactobacillus species in lipopolysaccharide (LPS)-induced colitis rats. LPS-sensitized rats were rendered colitic by colonic instillation of LPS (500 µg/rat) for 14 consecutive days. Concurrently, cell wall contents isolated from 10⁶ CFU of L. casei (LC), L. acidophilus (LA), and L. rhamnosus (LA) was given subcutaneously for 21 days, considering sulfasalazine (100 mg/kg, p.o.) as standard. The severity of colitis was assessed by body weight loss, food intake, stool consistency, rectal bleeding, colon weight/length, spleen weight, and histological analysis. Colonic inflammatory markers (myeloperoxidase activity, C-reactive protein, and pro-inflammatory cytokines) and oxidative stress markers (malondialdehyde, reduced glutathione, and nitric oxide) were also assayed. Cell wall contents of LC, LA, and LR significantly ameliorated the severity of colitis by reducing body weight loss and diarrhea and bleeding incidence, improving food intake, colon weight/length, spleen weight, and microscopic damage to the colonic mucosa. The treatment also reduced levels of inflammatory and oxidative stress markers and boosted anti-oxidant molecule. In conclusion, cell wall contents of LC, LA, and LR attenuate LPS-induced colitis by modulating immuno-inflammation and oxidative stress.

Berberine improves colitis by triggering AhR activation by microbial tryptophan catabolites

Inflammatory bowel diseases (IBD) are kind of recurrent inflammatory issues that occur in the gastrointestinal tract, and currently clinical treatment is still unideal due to the complex pathogenesis of IBD. Basically, gut barrier dysfunction is triggered by gut microbiota dysbiosis that is closely associated with the development of IBD, we thus investigated the therapeutic capacity of berberine (BBR) to improve the dysregulated gut microbiota, against IBD in rats, using a combinational strategy of targeted metabolomics and 16 s rDNA amplicon sequencing technology. Expectedly, our data revealed that BBR administration could greatly improve the pathological phenotype, gut barrier disruption, and the colon inflammation in rats with dextran sulfate sodium (DSS)-induced colitis. In addition, 16S rDNA-based microbiota analysis demonstrated that BBR could alleviate gut dysbiosis in rats. Furthermore, our targeted metabolomics analysis illustrated that the levels of microbial tryptophan catabolites in the gastrointestinal tract were significantly changed during the development of the colitis in rats, and BBR treatment can significantly restore such changes of the tryptophan catabolites accordingly. At last, our in vitro mechanism exploration was implemented with a Caco-2 cell monolayer model, which verified that the modulation of the dysregulated gut microbiota to change microbial metabolites coordinated the improvement effect of BBR on gut barrier disruption in the colitis, and we also confirmed that the activation of AhR induced by microbial metabolites is indispensable to the improvement of gut barrier disruption by BBR. Collectively, BBR has the capacity to treat DSS-induced colitis in rats through the regulation of gut microbiota associated tryptophan metabolite to activate AhR, which can greatly improve the disrupted gut barrier function. Importantly, our finding elucidated a novel mechanism of BBR to improve gut barrier function, which holds the expected capacity to promote the BBR derived drug discovery and development against the colitis in clinic setting.

miR-330 alleviates dextran sodium sulfate-induced ulcerative colitis through targeting IRAK1 in rats

Ulcerative colitis (UC) is a chronic multifactorial inflammatory bowel disease that severely impairs patients' life quality. microRNAs (miRNAs) have been reported to exhibit potential therapeutic effects in the management of UC. With the aim to investigate the regulatory effects of miR-330 on UC-related colon tissue damage and inflammation, a rat model of experimental colitis was established by oral administration of dextran sodium sulfate (DSS). DSS-treated rats showed mucosal damage, colonic inflammation, and elevated myeloperoxidase activity compared with the healthy controls. Dual-luciferase reporter assay confirmed the binding of interleukin-1 receptor-associated kinase 1 (IRAK1) and miR-330. Subsequently, rats were intracolonically injected with miR-330 argomir with/without administration of IRAK1 during DSS treatment. The miR-330 overexpression reduced DSS-induced colonic injury and the production of proinflammatory cytokines. The level of IRAK1 was negatively regulated by the expression of miR-330. IRAK1 overexpression abolished the protective effect of miR-330 on DSS-induced colonic inflammation and mucosal injury in rats. In conclusion, we clarify the role of miR-330 in pathogenesis of UC, suggesting miR-330 alleviated DSS-induced colitis by downregulating IRAK1, shedding lights on miR-330 as a therapeutic candidate for UC treatment.

Alternative stable states in the intestinal ecosystem: proof of concept in a rat model and a perspective of therapeutic implications

BACKGROUND

Chronic immune-mediated diseases are rapidly expanding and notoriously difficult to cure. Altered relatively stable intestinal microbiota configurations are associated with several of these diseases, and with a possible pre-disease condition (more susceptible to disease development) of the host-microbiota ecosystem. These observations are reminiscent of the behavior of an ecosystem with alternative stable states (different stable configurations that can exist under identical external conditions), and we recently postulated that health, pre-disease and disease represent such alternative states. Here, our aim was to examine if alternative stable states indeed exist in the intestinal ecosystem.

RESULTS

Rats were exposed to varying concentrations of DSS in order to create a wide range of mildly inflammatory conditions, in a context of diet-induced low microbiota diversity. The consequences for the intestinal microbiota were traced by 16S rRNA gene profiling over time, and inflammation of the distal colon was evaluated at sacrifice, 45 days after the last DSS treatment. The results provide the first formal experimental proof for the existence of alternative stable states in the rat intestinal ecosystem, taking both microbiota and host inflammatory status into consideration. The alternative states are host-microbiota ecosystem states rather than independent and dissociated microbiota and host states, and inflammation can prompt stable state-transition. Based on these results, we propose a conceptual model providing new insights in the interplay between host inflammatory status and microbiota status. These new insights call for innovative therapeutic strategies to cure (pre-)disease.

CONCLUSIONS

We provide proof of concept showing the existence of alternative stable states in the rat intestinal ecosystem. We further propose a model which, if validated in humans, will support innovative diagnosis, therapeutic strategy, and monitoring in the treatment of chronic inflammatory conditions. This model provides a strong rationale for the application of combinatorial therapeutic strategies, targeting host and microbiota rather than only one of the two in chronic immune-mediated diseases. Video Abstract.

Oleoylethanolamide Ameliorates Dextran Sulfate Sodium-Induced Colitis in Rats

Oleoylethanolamide (OEA) is an endogenous fatty acid ethanolamide known for its anti-inflammatory effects and its influence on gut microbiota composition; however, the effects of OEA in inflammatory bowel disease (IBD) remain unknown. During in vitro experiments, OEA downregulated the expression of tumor necrosis factor (TNF)-α and reduced phosphorylation of inhibitor of kappa (Iκ) Bα induced by lipopolysaccharide in human embryonic kidney cells. Moreover, OEA downregulated the expression of interleukin (IL)-8 and IL-1β and inhibited the phosphorylation of IκBα and p65 induced by TNF-α in human enterocytes (Caco-2). The effect of OEA in reducing the expression of IL-8 was blocked by the peroxisome proliferator-activated receptor (PPAR)-α antagonist. During in vivo experiments on rats, colitis was induced by the oral administration of 8% dextran sulfate sodium from day 0 through day 5, and OEA (20 mg/kg) was intraperitoneally injected once a day from day 0 for 6 days. OEA administration significantly ameliorated the reduction in body weight, the increase in disease activity index score, and the shortening of colon length. In rectums, OEA administration reduced the infiltration of macrophages and neutrophils and tended to reduce the histological score and the expression of inflammatory cytokines. Administration of OEA produced significant improvement in a colitis model, possibly by inhibiting the nuclear factor kappa B signaling pathway through PPAR-α receptors. OEA could be a potential new treatment for IBD.

Participation of Somatic Stem Cells, Recognized by a Unique A3 Antibody, in Mucosal Epithelial Regeneration in Dextran Sulfate Sodium (DSS)-Induced Rat Colonic Lesions

A3, generated as a monoclonal antibody against rat malignant fibrous histiocytoma cells, recognizes somatic stem cells in rats. We analyzed the distribution of A3-positive cells in dextran sulfate sodium (DSS)-induced colonic lesions consisting of regenerating mucosa and fibrosis. Male 6-week-old F344 rats were administered 5% DSS in drinking water for 5 to 7 days, and lesions at recovery stage were also examined. In untreated control adult colons, A3-positive cells are localized around the crypts where stem cell niche is formed. Histopathologically, in colons of DSS-administered rats, mucosal atrophy, inflammatory cell infiltration, and fibrosis were observed in the lamina propria; thereafter, mucosal epithelia were desquamated, and crypts were decreased gradually with decrease in surrounding A3-positive cells. At the early recovery stage, crypts showed regeneration with reappearance of A3-positive cells. Interestingly, A3-positive cells aggregated in desquamated mucosa surface of fibrosis. Aggregated A3-positive cells coexpressed with vimentin, Thy-1, and partly CK19 but did not react simultaneously with α-SMA. Likely, aggregated A3-positive cells may be rescue cells with nature of both mesenchymal and epithelial cells to maintain self-renewal after injury in the colon. A3 antibody would become a useful tool to investigate the participation of stem cells in rat colonic lesions.

Safranal Alleviates Dextran Sulfate Sodium-Induced Colitis and Suppresses Macrophage-Mediated Inflammation

Introduction: Crocus sativus (saffron) is widely used in China, Iran, and India for dyeing and as a food additive and medicinal plant. Safranal, as one of the main constituents of saffron, is responsible for its aroma and has been reported to have anticancer, antioxidant, and anti-inflammation properties. Objective: In this study, we investigated the anti-inflammatory effects of Safranal in RAW264.7 cells, bone marrow-derived macrophages (BMDMs), and dextran sulfate sodium (DSS)-induced colitis mice. Methods: Safranal toxicity was determined using an MTT assay. We evaluated the inhibitory effect of nitric oxide (NO) and levels of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in RAW264.7 cells and BMDMs. We assessed the inhibitory effect of pro-inflammatory cytokines, and the mRNA expressions of interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α), classical inflammatory pathways (MAPK and NF-κB), and the nuclear translocation factors AP-1 and NF-κB p65 were investigated. The in vivo anti-inflammatory effects of Safranal were assessed in a DSS-induced colitis model. DSS3.5% was used to induce colitis in mice with or without Safranal for 7 days; weight and disease activity index (DAI) were recorded daily. At the end of the experiment, the colon, mesenteric lymph nodes (MLNs), and spleen were collected for flow cytometry, ELISA, and Western blot analysis. Results: Safranal suppressed NO production, iNOS, and COX-2 in lipopolysaccharide (LPS)-stimulated RAW264.7 cells and BMDMs. Safranal decreased the production and mRNA expression of IL-6 and TNF-α in the RAW264.7 cell line and inhibited the phosphorylation and nuclear translocation of components of the MAPK and NF-κB pathways. Safranal alleviated clinical symptoms in the DSS-induced colitis model, and colon histology showed decreased severity of inflammation, depth of inflammatory involvement, and crypt damage. Immunohistochemical staining and flow cytometry showed reduced macrophage infiltration in colonic tissues and macrophage numbers in MLNs and the spleen. The levels of colonic IL-6 and TNF-α also decreased in Safranal-treated colitis mice. This study elucidates the anti-inflammation activity of Safranal, which may be a candidate for inflammatory bowel syndrome (IBD) therapy.

Microbiota of Inflammatory Bowel Disease Models

Gut microbiome plays an important role in inflammatory bowel disease (IBD), a group of intestinal chronic inflammation conditions that affect a large population. The animal models of IBD have long been established on basis of pathological features, but their ability to recapitulate patient gut microbiota is unknown. We investigated and compared the composition and biodiversity of bacterial population in the fecal samples from rat models of the two IBD subtypes, and compared them with patient samples. Our analyses revealed that inflammation reduces overall microbiome diversity and increased variation between individuals. We identified specific microbial signatures associated with the two IBD subtypes that were consistent between the animal models and human IBD patients, suggesting that the animal models can partially recapitulate the microbiota in human diseases. Furthermore, metagenome prediction analysis suggested microbial functions that were likely altered by host-microbiota interactions in IBD models.

Berberine Upregulates P-Glycoprotein in Human Caco-2 Cells and in an Experimental Model of Colitis in the Rat via Activation of Nrf2-Dependent Mechanisms

Downregulation of P-glycoprotein (P-gp) is implicated in the pathophysiology of inflammatory bowel disease (IBD). Berberine, a principal isoquinoline alkaloid extracted from Berberis species, has been reported to exhibit therapeutic potential in IBD. In this study, we used a dextran sulfate sodium (DSS)-induced colitis rat model to evaluate the effect of berberine on P-gp and explore its mechanism of action. Berberine treatment improved DSS-induced colitis symptoms, attenuated inflammatory markers (myeloperoxidase, tumor necrosis factor-α, and interleukin-1β and -6), and enhanced P-gp expression in a dose-dependent manner. Although colonic expression of the P-gp-related nuclear receptor pregnane X receptor and transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) were downregulated in the colitis model, gene and protein expression analysis revealed that berberine treatment reversed only the downregulation of Nrf2. In vitro studies using Caco-2 cells showed that the multidrug resistance 1 (MDR1) gene and P-gp protein were upregulated by berberine in a dose- and time-dependent manner. Significant upregulation of the MDR1 gene by berberine was abrogated by Nrf2 silencing, indicating that the Nrf2-mediated pathway was responsible for this activation. Luciferase assays showed a dose-dependent increase in Nrf2 reporter gene activity after berberine treatment in Caco-2 cells, with a significant 2-fold elevation at 2.5 μM berberine, suggesting that berberine is a strong Nrf2 activator. These results indicate the possible involvement of Nrf2-mediated upregulation of P-gp in the therapeutic effect of berberine on colitis and highlight the potential of P-gp and/or Nrf2 as new therapeutic targets for IBD.

Increased CD4+CD45RA-FoxP3low cells alter the balance between Treg and Th17 cells in colitis mice

AIM

To investigate the role of regulatory T cell (Treg) subsets in the balance between Treg and T helper 17 (Th17) cells in various tissues from mice with dextran sulfate sodium-induced colitis.

METHODS

Treg cells, Treg cell subsets, Th17 cells, and CD4⁺CD25⁺FoxP3⁺IL-17⁺ cells from the lamina propria of colon (LPC) and other ulcerative colitis (UC) mouse tissues were evaluated by flow cytometry. Forkhead box protein 3 (FoxP3), interleukin 17A (IL-17A), and RORC mRNA levels were assessed by real-time PCR, while interleukin-10 (IL-10) and IL-17A levels were detected with a Cytometric Beads Array.

RESULTS

In peripheral blood monocytes (PBMC), mesenteric lymph node (MLN), lamina propria of jejunum (LPJ) and LPC from UC mice, Treg cell numbers were increased (P < 0.05), and FoxP3 and IL-10 mRNA levels were decreased. Th17 cell numbers were also increased in PBMC and LPC, as were IL-17A levels in PBMC, LPJ, and serum. The number of FrI subset cells (CD4⁺CD45RA⁺FoxP3^low) was increased in the spleen, MLN, LPJ, and LPC. FrII subset cells (CD4⁺CD45RA^-FoxP3^high) were decreased among PBMC, MLN, LPJ, and LPC, but the number of FrIII cells (CD4⁺CD45RA^-FoxP3^low) and CD4⁺CD25⁺FoxP3⁺IL-17A⁺ cells was increased. FoxP3 mRNA levels in CD4⁺CD45RA^-FoxP3^low cells decreased in PBMC, MLN, LPJ, and LPC in UC mice, while IL-17A and RORC mRNA increased. In UC mice the distribution of Treg, Th17 cells, CD4⁺CD45RA^-FoxP3^high, and CD4⁺CD45RA^-FoxP3^low cells was higher in LPC relative to other tissues.

CONCLUSION

Increased numbers of CD4⁺CD45RA^-FoxP3^low cells may cause an imbalance between Treg and Th17 cells that is mainly localized to the LPC rather than secondary lymphoid tissues.

RORγt+ cells selectively express redundant cation channels linked to the Golgi apparatus

Retinoid-related orphan receptor gamma t (RORγt) is a master transcription factor central to type 17 immunity involving cells such as T helper 17, group 3 innate lymphoid cells or IL-17-producing γδ T cells. Here we show that the intracellular ion channel TMEM176B and its homologue TMEM176A are strongly expressed in these RORγt⁺ cells. We demonstrate that TMEM176A and B exhibit a similar cation channel activity and mainly colocalise in close proximity to the trans-Golgi network. Strikingly, in the mouse, the loss of Tmem176b is systematically associated with a strong upregulation of Tmem176a. While Tmem176b single-deficiency has no effect on the course of experimental autoimmune encephalomyelitis, T cell or DSS-induced colitis, it significantly reduces imiquimod-induced psoriasis-like skin inflammation. These findings shed light on a potentially novel specific process linked to post-Golgi trafficking for modulating the function of RORγt⁺ cells and indicate that both homologues should be simultaneously targeted to clearly elucidate the role of this intracellular ion flow.